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1.
The recent UK operation to recapture the Falkland Islands demonstrated the crisis and wartime utility of civilian merchant vessels in assisting military operations in distant areas. Over 50 merchantmen — many rapidly converted — were taken up from trade and served in a variety of vital logistic and support roles; as troop and hospital ships, aircraft transporters, repair ships and munitions carriers, to mention but a few. 1 In addition to the lessons for amphibious landing operations and air defence of surface naval combatants, a recent issue of Morskoi Sbornik pointed to the importance of peacetime arrangements for transfer of merchant shipping to naval control and the role of large container ships as aircraft transporters and operating platforms for Harrier aircraft providing air defence of the Royal Navy's ‘mobile rear’ en route for the operational area. 2 The time is perhaps propitious for an examination of the dimensions, make-up and peacetime roles of the Soviet civilian fleets, focusing on the contribution made to Soviet economic and military objectives by the USSR Ministry of the Maritime Fleet.  相似文献   

2.
These articles concern two countries with broadly similar diplomatic and military alignments but with defence policies which appear to be evolving in opposite directions. In the first article, Keith Speed MP, Parliamentary Under-secretary of State for the Royal Navy until May 1981, offers a critique of UK naval policy as outlined in the Defence White Paper of June 1981. In the second article, Kaiji Yamaguchi, a professor of international law and member of the Japanese Navy, analyses Japan's defence imperatives in the light of Soviet activity in North-east Asia and US pressure on the Japanese government to increase its defence budget. Both articles highlight the dilemma posed by Soviet expansionism requiring a positive response from the West and a world recession which demands reductions in public spending.  相似文献   

3.
Keith Speed 《Marine Policy》1982,6(2):150-151
These articles concern two countries with broadly similar diplomatic and military alignments but with defence policies which appear to be evolving in opposite directions. In the first article, Keith Speed MP, Parliamentary Under-secretary of State for the Royal Navy until May 1981, offers a critique of UK naval policy as outlined in the Defence White Paper of June 1981. In the second article, Kaiji Yamaguchi, a professor of international law and member of the Japanese Navy, analyses Japan's defence imperatives in the light of Soviet activity in North-east Asia and US pressure on the Japanese government to increase its defence budget. Both articles highlight the dilemma posed by Soviet expansionism requiring a positive response from the West and a world recession which demands reductions in public spending.  相似文献   

4.
This article introduces a new feature in MARINE POLICY. The aim of the series is to present the views of specialists on questions of maritime strategy and naval policy. Future articles will focus on three broad areas: the major political and technical issues involved in framing future naval strategy; analyses of individual states' strategic outlooks and naval procurement policies; and surveys of the arenas of potential maritime conflict. Professor Peter Nailor of the Royal Naval College, Greenwich, UK, begins the series with a wide-ranging consideration of the issues confronting naval powers in the development of future maritime strategy and defence policies.  相似文献   

5.
Aerial photographs from 1972, 1985 and 2000 were analyzed to obtain measurements of coastal change in the Mackenzie Delta region of the Beaufort Sea. Changes from 1972 to 2000 are dominated by retreat of the shoreline with average annual retreat rates of –0.6 m a–1, but ranging as high as –22.5 m a–1. Rates vary significantly both between and within zones of similar exposure, morphology and coastal geology with the highest average rates located in areas that are most exposed to northwest winds. In general, decadal-scale rates of change have remained constant during the 28 years encompassed by this study.  相似文献   

6.
Fluxes contributing to the particulate carbonate system in deep-sea sediments were investigated at the BENGAL site in the Porcupine Abyssal Plain (Northeast Atlantic). Deposition fluxes were estimated using sediment traps at a nominal depth of 3000 m and amounted to 0.37±0.1 mmol C m−2 d−1. Dissolution of carbonate was determined using flux of total alkalinity from in situ benthic chambers, is 0.4±0.1 mmol C m−2 d−1. Burial of carbonate was calculated from data on the carbonate content of the sediment and sedimentation rates from a model age based on 14C dating on foraminifera (0.66±0.1 mmol C m−2 d−1). Burial plus dissolution was three times larger than particle deposition flux which indicates that steady-state is not achieved in these sediments. Mass balances for other components (BSi, 210Pb), and calculations of the focusing factor using 230Th, show that lateral inputs play only a minor role in this imbalance. Decadal variations of annual particle fluxes are also within the uncertainty of our average. Long-term change in dissolution may contribute to the imbalance, but can not be the main reason because burial alone is greater than the input flux. The observed imbalance is thus the consequence of a large change of carbonate input flux which has occured in the recent past. A box model is used to check the response time of the solid carbonate system in these sediments and the time to reach a new steady-state is in the order of 3 kyr. Thus it is likely that the system has been perturbed recently and that large dissolution and burial rates reflect the previously larger particulate carbonate deposition rates. We estimate that particulate carbonate fluxes have certainly decreased by a factor of at least 3 and that this change has occurred during the last few centuries.  相似文献   

7.
Vertical profiles of dimethylsulfide (DMS) and β-dimethylsulfoniopropionate, particulate (pDMSP) and dissolved (dDMSP), were measured biweekly in the upper 140 m of the Sargasso Sea (32°10′N, 64°30′W) during 1992 and 1993. DMS and pDMSP showed strong, but different, seasonal patterns; no distinct intra-annual pattern was observed for dDMSP. During winter, concentrations of DMS were generally less than 1 nmol l−1 at all depths, dDMSP was less than 3 nmol l−1 and pDMSP was less than 8 nmol l−1. In spring, concentrations of both dDMSP and pDMSP rose, on a few occasions up to 20 nmol l−1 in the dissolved pool and up to 27 nmol l−1 in the particulate pool. These increases, due to blooms of DMSP-containing phytoplankton, resulted in only minor increases in DMS concentrations (up to 4 nmol l−1). Throughout the summer, the concentrations of DMS continued to increase, reaching a maximum in August of 12 nmol l−1 (at 30 m depth). There was no concomitant summer increase in dDMSP or pDMSP. The differences among the seasonal patterns of DMS, dDMSP, and pDMSP suggest that the physical and biological processes involved in the cycling of DMS change with the seasons. There is a correlation between the concentration of DMS and temperature in this data set, as required by some of the climate feedback models that have been suggested for DMS. A full understanding of the underlying processes controlling DMS is required to determine if the temperature-DMS pattern is of significance in the context of global climate change.  相似文献   

8.
The post-nuclear time-series curves of Δ14C from corals at different locations in the surface of the Pacific Ocean show a variation in the shape, amplitude and timing of the peak, with the subtropical records peaking first, followed by the western, and then eastern tropical records with lower maxima. This work takes an in-depth look at the processes that shape the time histories of Δ14C in surface waters at different locations in the Pacific. A one-dimensional (1-D) model is used to examine whether convection and diffusion can delay the peaking of the Δ14C time series. Using the three-dimensional (3-D) MIT general circulation model (GCM), the distribution and evolution of Δ14C is simulated “offline” from 1955 onwards at 1° resolution globally. The GCM is used to tease apart the contribution of various processes, viz. advection, air–sea flux, convection and diffusion, to altering the Δ14C content of surface waters at different locations in the Pacific. A time history of 14C column inventories from the model is constructed to examine the role of horizontal advection in supplying tropical locations with 14C much after the peak atmospheric flux. This model analysis supports the idea of 14C-rich waters from the subtropics being transported to the western tropics via the subsurface, and then being advected eastward in the equatorial undercurrent and upwelled in the east.  相似文献   

9.
In order to validate wind vectors derived from the NASA Scatterometer (NSCAT), two NSCAT wind products of different spatial resolutions are compared with observations by buoys and research vessels in the seas around Japan. In general, the NSCAT winds agree well with the wind data from the buoys and vessels. It is shown that the root-mean-square (rms) difference between NSCAT-derived wind speeds and the buoy observations is 1.7 ms–1, which satisfies the mission requirement of accuracy, 2 ms–1. However, the rms difference of wind directions is slightly larger than the mission requirement, 20°. This result does not agree with those of previous studies on validation of the NSCAT-derived wind vectors using buoy observations, and is considered to be due to differences in the buoy observation systems. It is also shown that there are no significant systematic trends of the NSCAT wind speed and direction depending on the wind speed and incidence angle. Comparison with ship winds shows that the NSCAT wind speeds are lower than those observed by the research vessels by about 0.7 ms–1 and this bias is twice as large for data observed by moving ships than by stationary ships. This result suggests that the ship winds may be influenced by errors caused by ship's motion, such as pitching and rolling.  相似文献   

10.
The diversity, abundance and biomass of microzooplankton in Cochin backwaters were studied for the first time during pre-summer monsoon to peak of summer monsoon (April–July 2003) to understand the impact of large freshwater influx. Microzooplankton abundance and biomass were highest during pre-summer monsoon (av. 3817 ind. L−1 and 146 μg C L−1) that declined with the onset (av. 2052 ind. L−1 and 45 μg C L−1) and peak (av. 409 ind. L−1 and 10 μg C L−1) summer monsoon. Species diversity, richness and evenness of microzooplankton also showed similar trends as that of abundance and biomass. Grazing experiment showed that microzooplankton consumes 43 ± 1% of the daily phytoplankton standing stock during the high saline condition (27.5). Low abundance of microzooplankton during summer monsoon period (1/8 of the pre-summer monsoon value) along with the concomitant occurrence of low mesozooplankton (1/8 times of pre-summer monsoon value) suggests that there could be a general lack of planktonic grazers. This would result in a weak transfer of primary and bacterial carbon to higher trophic levels, eventually leaving behind much unconsumed basic food in the estuary during summer monsoon. Thus a major portion of the primary carbon either settles down or gets transported to the coastal regions during monsoon. High flushing of Cochin backwaters also facilitates faster removal of primary producers to the coastal regions during monsoon.  相似文献   

11.
Wind-driven cyclonic eddies are hypothesized to relieve nutrient stress and enhance primary production by the upward displacement of nutrient-rich deep waters into the euphotic zone. In this study, we measured nitrate (NO3−), particulate carbon (PC), particulate nitrogen (PN), their stable isotope compositions (δ15N-NO3−, δ13C-PC and δ15N-PN, respectively), and dissolved organic nitrogen (DON) within Cyclone Opal, a mature wind-driven eddy generated in the lee of the Hawaiian Islands. Sampling occurred in March 2005 as part of the multi-disciplinary E-Flux study, approximately 4–6 weeks after eddy formation. Integrated NO3− concentrations above 110 m were 4.8 times greater inside the eddy (85.8±6.4 mmol N m−2) compared to the surrounding water column (17.8±7.8 mmol N m−2). Using N-isotope derived estimates of NO3− assimilation, we estimated that 213±59 mmol m−2 of NO3− was initially injected into the upper 110 m Cyclone Opal formation, implying that NO3− was assimilated at a rate of 3.75±0.5 mmol N m−2 d−1. This injected NO3− supported 68±19% and 66±9% of the phytoplankton N demand and export production, respectively. N isotope data suggest that 32±6% of the initial NO3− remained unassimilated. Self-shading, inefficiency in the transfer of N from dissolved to particulate export, or depletion of a specific nutrient other than N may have led to a lack of complete NO3− assimilation. Using a salt budget approach, we estimate that dissolved organic nitrogen (DON) concentrations increased from eddy formation (3.8±0.4 mmol N m−2) to the time of sampling (4.0±0.09 mmol N m−2), implying that DON accumulated at rate of 0.83±1.3 mmol N m−2 d−1, and accounted for 22±15% of the injected NO3−. Interestingly, no significant increase in suspended PN and PC, or export production was observed inside Cyclone Opal relative to the surrounding water column. A simple N budget shows that if 22±15% of the injected NO3− was shunted into the DON pool, and 32±6% is unassimilated, then 46±16% of the injected NO3− remains undocumented. Alternative loss processes within the eddy include lateral exchange of injected NO3− along isopycnal surfaces, remineralization of PN at depth, as well as microzooplankton grazing. A 9-day time series within Cyclone Opal revealed a temporal depletion in δ15N-PN, implying a rapid change in the N source. A change in NO3− assimilation, or a shift from NO3− fueled growth to assimilation of a 15N-deplete N source, may be responsible for such observations.  相似文献   

12.
Our experience in DNA alteration assessment tells us that aquatic vertebrates, in general, and also some of the invertebrates, by living in polluted areas acquire altered DNA; DNA alterations being defined either as single-strand breaks, and/or alkali sensitive or single-strand specific nuclease-cleavable sites (sse). This can be shown by several methods: (i) Alkaline filter elution;1 (ii) fluorescence analysis of DNA unwinding;2 (iii) alkaline sucrose density gradient centrifugation;3 (iv) alkaline unwinding analysis with hydroxyapatite differentiation;4 (v) nucleoid sedimentation analysis;5 (vi) supercoiled DNA relaxation detection by electrophoresis;6 and (vii) measurement of DNA molecular weight distributions with the electron microscope.7 The amount of sse per DNA mass can be a function of either an increased activity of DNA damaging agents or agents that inhibit DNA repair. Among DNA damaging agents are polycyclic aromatic hydrocarbons (PAH), that can cause sse by the ‘fast effect’8 or after induction upon uptake, through the action of mixed function oxygenase (MFO). Since MFO induction within certain limits is a function of PAH concentration measurement of this enzyme activity enables at least partial interpretation of the DNA alteration status, which can be a two-phase process.  相似文献   

13.
To analyse material transport in inland seas, a horizontal two-dimensional dispersion equation is derived, and the dispersion coefficient due to the combined effect of vertical turbulent mixing and vertical shear of both a steady current and a tidal current is studied. In the present study, the assumption that velocity is uniform in horizontal planes is not necessary, and velocity has a free vertical profile; thus the dispersion coefficient formulated is general, and is represented by a tensor of the second order. The properties of the dispersion coefficient in the horizontal two-dimensional dispersion model are also investigated, and it is shown that the time-averaged dispersion coefficient due to the tidal current over a tidal period is approximately half that due to the steady current, if the velocity amplitude and the vertical profile of the tidal current are the same as those of the steady current (a similar result was presented byBowden (1965) for horizontal one-dimensional models). Finally, the dispersion coefficient in Hiuchi-Nada (Hiuchi Sound) in the central part of the Seto Inland Sea is evaluated by using the model. The values of the dispersion coefficient in that region range from 103 cm2 s–1 to 105 cm2 s–1 when vertical turbulent diffusivity is taken to be 50 cm2 s–1.  相似文献   

14.
Heterotrophic mineralization of dissolved organic nitrogen (DON) can be a major source of N for primary producers. During the summer growing season in mesooligotrophic Castle Lake, dissolved inorganic nitrogen (DIN) is often below detection (<0.1 μg-atom N l−1) whereas DON can vary between 7 and 17 μg-atom N. The heterotrophic metabolism of glutamate resulted in the recycling of both carbon and nitrogen, but not at the same rate. The uptake of 15N- and 14C-labeled glutamate showed that C was preferentially assimilated relative to N resulting in an N-mineralization rate of 2.5–3.0 ng-atom N l−1 h−1. This suggests that heterotrophs in Castle Lake are not N-deficient, and metabolism of organic compounds results in the release of DIN which is available for primary production.  相似文献   

15.
Food web interactions and the response of Pacific salmon to physical processes in the North Pacific Ocean over interannual and interdecadal timescales are explored using naturally occurring stable isotope ratios of carbon (13C/12C) and nitrogen (15N/14N). Stable isotope analyses of five species of sexually mature North Pacific salmon from Alaska (Oncorhynchus spp.) cluster into three groups: chinook salmon (O. tshawytscha) have the highest values, followed by coho (O. kisutch), with chum (O. keta), sockeye (O. nerka), and pink (O. gorbuscha) together having the lowest values. Although detailed isotopic data on salmon prey are lacking, there are limited data on relevant prey items from areas in which they are found in high abundance. These data suggest that the characteristics of the sockeye, pink and chum we have analyzed are compatible with their diets including open ocean squid and zooplankton, which are in general agreement with stomach content analyses. Isotope relationships between muscle and scale show consistent relationships for both δ13C (R2=0.98) and δ15N (R2=0.90). Thus, scales, which have been routinely archived for many systems, can be used for retrospective analyses. Archived sockeye salmon scales spanning 1966–1999 from Red Lake, Kodiak Island, Alaska were analyzed for their stable isotope ratios of carbon and nitrogen. The δ15N record displays a decreasing trend of ˜3‰ from 1969–1982 and an increasing trend of ˜3‰ from 1982–1992, while the variations in δ13C are relatively minor. These trends may result from factors such as shifts in trophic level of feeding and/or feeding location, or may originate at the base of the food web via changes in processes such as nutrient cycling or primary productivity. Detailed studies on prey isotopic variability and its controls are needed to distinguish between these factors, and thus to improve the use of stable isotope analysis as a tool to learn more about present and past ecosystem change in the North Pacific and its relation to climatic change.  相似文献   

16.
Recent measurements indicate the transatlantic extent of the Namib Col Current at depths of 1300–3000 m near Lat. 22°S in the South Atlantic Ocean. This current forms a continuous circulation structure from the Namib Col on the Walvis Ridge to the western trough, though its characteristic change as deep water with varying properties enters and leaves the current owing to a meridional flow component. Transport estimates from hydrographic sections on the Walvis Ridge and at 15°W near the crest of the Mid-Atlantic Ridge indicate a strength of about 3 × 106 m3 s−1. The current is part of a larger-scale eastward flow at Lon. 25°W; transport estimates across the salinity maximum core there show a similar strength. Associated with this high-salinity high-oxygen current is a basin-wide front in these properties of varying intensity (weaker in the east) marking the transition to deep water whose North Atlantic characteristics have been partly erased by mixing with Circumpolar Deep Water in the southwest South Atlantic. The water which finally crosses the Walvis Ridge is supplied both by the eastward flow of this (diluted) North Atlantic Deep Water and by a general southeastward interior flow from the northern Angola Basin. Evidence suggests that this deep water continues south in the eastern Cape Basin, leaving the South Atlantic near the African continent.  相似文献   

17.
This is a paper from the Swedish research project ‘The coastal zone—scientific criteria for planners’. The goal has been to establish simple, general scientific methods for management of Swedish coastal waters. In this paper the focus is on a set of empirical data from 21 so-called type areas and on the exchange of surface water. The working hypothesis has been that the water retention (or residence) time is regulated by the morphometry. The theory has been verified. It has been shown that the water retention time can be determined from a formula based on only two key morphometric parameters, the exposure and the mean coastal width. It provides an 86% degree of explanation (r2=0·86) of the variation in empirically determined retention times and can be physically linked to the basic mass balance equation. The formula is valid for the bioproductive season (May–Oct.) and for small (1–100 km2) Swedish coastal areas. It cannot be directly applied to areas affected by heavy tides.  相似文献   

18.
Specific effects of tributyltin (TBT) on Crassostrea gigas—valve thickening, and Nucella lapillus—imposex, were measured on local populations, relatively clean unaffected species from England were transferred to the Netherlands and exposed during six weeks to ambient TBT concentrations. Near marinas 50% of the exposed species were sterile after six weeks. In general, no dissolved butyltins were detected in the Rhine and Scheldt estuaries. In 1988 TBT concentrations in marinas ranged from 120 to 4000 ng litre−1. In sediments (fraction <60 μm) and suspended particulate matter TBT concentrations reached up to 1200 ng g−1. TBT concentrations in mussel tissue ranged from <1 to 2300 ng g−1 based on a dry weight. In 1989 concentrations of dissolved TBT ranged from <0·1 to 7200 ng litre−1. In 1989 a seasonal study in the marina of Colijnsplaat showed that dissolved butyltins increased from April to the end of May due to the launching of freshly painted boats, and decreased afterwards.  相似文献   

19.
Few data on dissolved trace metals in rivers and estuaries are presently available. This paper is an attempt to provide additional data on dissolved concentrations obtained in polluted and so-called unpolluted river estuarine systems. Data for two major French rivers (Gironde, Rhône) have been compared with the Chinese Yellow River (Huanghe) and Yangtze River (Changjiang). Dissolved Cd concentrations have been measured by differential pulse anodic stripping voltammetry. Average concentrations range from 15 ng kg−1 to 50 ng kg−1 (0.13–0.45 nmol kg−1) in the French rivers and are below 4 ng kg−1 (0.040 nmol kg−1) in the Chinese rivers.In all the estuaries studied the dissolved Cd concentrations depict a systematic bulge in the mixing zone which is attributed largely to remobilization processes from particulate matter when the chlorinity increases. Other parameters that may also play a significant role for remobilization are discussed. The processes concerned lead us to reassess the net Cd river input to the oceans, and this should be taken into account for a more precise evaluation of the residence time of oceanic Cd.  相似文献   

20.
The subarctic North Pacific is one of the three major high nitrate low chlorophyll (HNLC) regions of the world. The two gyres, the NE and the NW subarctic Pacific gyres dominate this region; the NE subarctic Pacific gyre is also known as the Alaska Gyre. The NE subarctic Pacific has one of the longest time series of any open ocean station, primarily as a result of the biological sampling that began in 1956 on the weathership stationed at Stn P (50°N, 145°W; also known as Ocean Station Papa (OSP)). Sampling along Line P, a transect from the coast (south end of Vancouver Island) out to Stn P has provided valuable information on how various parameters change along this coastal to open ocean gradient. The NW subarctic Pacific gyre has been less well studied than the NE gyre. This review focuses mainly on the NE gyre because of the large and long term data set available, but makes a brief comparison with the NW gyre. The NE gyre has saturating NO3 concentrations all year (winter = about 16 μM and summer = about 8 μM), constantly very low chlorophyll (chl) (usually <0.5 mg m−3) which is dominated by small cells (<5 μm). Primary productivity is low (about 300–600 mg C m−2 d−1 and varies little (2 times) seasonally. Annual primary productivity is 3 to 4 times higher than earlier estimates ranging from 140 to 215 g C m−2 y−1. Iron limits the utilization of nitrate and hence the primary productivity of large cells (especially diatoms) except in the winter when iron and light may be co-limiting. There are observations of episodic increases in chl above 1 mg m−3, suggesting episodic iron inputs, most likely from Asian dust in the spring/early summer, but possibly from horizontal advection from the Alaskan Gyre in summer/early fall. The small cells normally dominate the phytoplankton biomass and productivity, and utilize the ammonium produced by the micrograzers. They do not appear to be Fe-limited, but are controlled by microzooplankton grazers. The NW Subarctic Gyre has higher nutrient concentrations and a shallower summer mixed depth and photic zone than Stn P in the NE gyre. Chl concentrations tend to be higher (0.5 to 1.5 μg L−1) than Stn P, but primary productivity in the summer is similar to Stn P (600 mg C m−2 d−1). There are no seasonal data from this gyre. Iron enrichment experiments in October, resulted in an increase in chl (mainly the centric diatom Thalassiosira sp.) and a draw down of nitrate, suggesting that large phytoplankton are Fe-limited, similar to Stn P.  相似文献   

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